Block-signal system.



PATENTED JUNE 11, 1907.

L A. HAWKINS. BLOCK SIGNAL SYSTENL.

APPLIUATION FILED JAN. 11, 1907 MENTUR LAZE?ENUE A. BY

ATTYI YKKf'SEES/ UNITED STATES.

PATENT OFFICE.

LAURENCE A. HAWKINS, OF SCHENECTADY, NEW YORK, ASSIGN OR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

BLOCK-SIGNAL SYSTEM.

Specification of Letters Patent.

Patented June 11, 1907.

Application filed January 11,1907. Serial No. 351,834.

' 342,455, filed November 8, 1906. In that application I described a block signal system for electricallyoperated roads havin both rails conductively continuous for al currents (as distinguished from the systems employing inductive bonds for separating the rails into blocks), with transformers and signal controlling relays connected at intervals acrosss the rails, and means'controlled by an approaching train for closing the circuit of a transformer ahead of a train. The system was arranged to operate on the normal danger plan, since with this method of opcrating the signals the transformers may be normally open-circuited and economy of current secured. In order to close the circuit of a transformer ahead of a train, I made use, in my former application, of an electromagnet or relay connected to a short insu lated rail-length, which served as a contact to be closed by a train passing over it. For

such insulated section insulating .rail j oints are, of course, required, and these joints are objectionable witlr respect .to maintenance, since they wear out rapidly in service and I must befr'equently replaced.

The object of my present invention is to provide means for closing the circuit ofa transformer ahead of a train, without employing any insulated joints whatever, and without resorting to circuit-closers mechanically operated by a .train. I secure this sesult by connecting at intervals across the rails sources of low-voltage high-freuency current with relays in circuit with t e. sources controlhng the transformers.

'These sources may be of sufliciently low voltage and sufiiciently high frequency, so that when they are placed at some distance from any other devices connected across the rails-thecurrent-flow from these sources is small, ,buta trainis directly over one of them, the current in that source rises to several times its normal value. This rise of current I utilize to actuate the relay con. trollin the transformer circuit.

My invention will best be understood by reference to the accompanying drawing, which shows diagrammatically a block signal system arranged in accordance withmy invention.

In the drawing, A represents the rails of an electric road, both of which are made conductively continuous, so as to serve as return conductor for the power-current.

B represents the third rail, or other supply conductor, connected to one terminal of the power-generator C; the other terminal of which may be connected to the rails A throughthe' differential choke-coil c. This generator may furnish either direct current or low-frequency alternating current.

D represents a bi h-frequency alternating current generator wliich furnishes the power for the signal circuits.

E E represent transformers, the primaries of which are connected to the transmission wires (1, which extend from the generator D along the track, and the secondaries of which are connected across the rails through a small resistance e, which may be employed to limit the flow of current from the trans former when short-circuited by a train. The transformers E E are normally open-circuited on either their primary or secondary side. I have shown the secondary opencircuited, but it will be understood that if the relative values of current and voltage make it referable, the primary may be open circuite instead.

F F represent track relays responsive only to alternating-current, if direct current is used for the power circuits; or to alternating current of a predetermined frequency only, if alternating current is used for the power circuits. I have illustrated a relay of the induction type having a short-circuited secondary member f, carrying the relay contacts, and co-operating windings, one of which, f, is connected across the track, and the other, f supplied from the line wires d.,through any base-controlling device, such as the con enser f arranged to give a phase-displacement between the currents in the two windings f and *G G represent electromagnets controlling transformer, and a normally-closed contact suitable operating mechanisms indicated diaprovide transformers K K, and relays L L frequency of the voltage impressed by these 1 relays will not be affected by the voltage implied directly from the transformers E E.

nearest signal devices,

may readily be arranged'to -sup ly-to therails a voltage which, re ardless of-itsamount ,relays F F,

the circuits of transformers E and E and relays F and F, respectively, by means of a normally-open contact in series with the in series with the relay. The electromagnets G G are shown'supplied from batteries g, 9, but any other suitable source of current may be employed for these magnets. For instance, if the magnets are. arranged to oper ate on alternating current, they may be sup-- 'lhese'magnets are normally deenergized,

H H represent signals providedwith any,

grammatically by .the' solenoids TI. The signals are normally "at danger with their" operating mechanisms de-energized.

i represents any suitable source of current for the operating mechanism. 7

Each signal isprovided with contacts h, h and 7L2 for purposesv that will be hereinafter explained.

The system, as thus far described, is iden-- tical with that disclosed in my former application, above referred to,'but in place of .the short rail section of my former application, I

in circuit with the transformers. These transformers are connected on their primar sides to the line, wires (2, and their, secon aries, which are connected across the rails," are designed for a low voltage. Since the j transformers on the rail is high, and since the voltage of the transformers is low, the amount of current which will flow from the transformers.- to the nearest signal devices connected across the rails Willbevery small the transformer is at some distance from'the In order to reduce this How to a minimum, the transformer may be placed in the middle of a block, though a position at the exact center of a block is not necessary if the voltage is sufficiently low. Ifjthe transformersK K are some distance away from the nearest relays F F, and if the transformer voltage is sufficiently low,-,the

pressed on the rails by these transformers, but as a further safer-guard, the transformers will not affect these re ays at all. ,"Tliis re-; sult might be secured. b supplying to the! transformers 'K' K. a equency different from that'su plied to tranSformersEE and.

buta sim ler arrangementforf securing the same res t consists in placing. the condensers k'lc in series 'With-tllfi. trans-1 former primaries so as to shift phase. ofi the voltage sup lied by these trainsformersi to the track. n thisway not-onl the relays F F be made independentiof the current supplied by the transformers K K",

again, as the train passes beyond it, electronragnet G remains energized. Now, let it be but also the relays L L may be made. independent of the current suppliedby trans-:- formersEE. I

When no trains arerunning, the conditionsof the circuits are as shownin'the draW- ing. The transformersfE-E are open-circuited at the contacts of-the electromagnets G G. The transformers K K have their circuits closed, but for reasons ,above explained, the amount of current flowing throu h their secondaries is small, so'that re- L are not sufiiciently-energized "to close their contacts. When a train reaches transformer K, it shortcircuits the transformer through the track windingof the re. lay L, thereby greatly increasing the currentin the transformer and relay, so as to cause the relay to close itscontact. .This establishes 'a circuit from the lower rail A' through the contacts of relay L, battery g, electromagnet G, upper rail A and throu h the axles of the train to the lower rail. -i agnet G is, consequently, energized and draws up itsarmature, closing a maintaining circuit for itself, which may be traced from the lower-- terminal of battery g through contacts h of signal H, through upper armature of magnet G, and through the magnet winding to the 11 per terminal of battery g. Consequently, aithough relay L soon opens its contacts assumed that ma et G has been energized in the manner described above, and that a train is approaching, as indicated by the arrow. The ener' iz'ation of magnet G has opened the A circuito track windingf of relay F at the back contact of thelower armature of mag: net'G, and hasclosed the secondary circuit of transformer. Eat the front contact; of that armature Transformer Econsequently im presses an alternating current'voltage across the track-rails, and if the block between trans-- former E and relay F is unoccupied, relay F will be energized; closing its contacts and thereby energizin the operating mechanism I of signal H, whic draws the'isignal to clear position. In the movement otthe signal to clear, movable contact his brought into en-- 'gagement with its stationary contacts, there by closing a second circuit for transformer E;

Afterthis circuit is closed, contacts h and 7L2 u leave their stationary contacts, thereby breaking the maintaining circuit-ef magnet G, and atthe same time introducing 'a second break into the track Winding "of; relay F. Magnet .G consequently drops its armatures,

but the'circuit of transformer E is main tained closed', and the circuit of the track tinues until. the trainyin passing signal comes close enough totransformer Elto pull down its voltage sufliciently to deenerg'ize relay F.- When this occurs, relay F. o us its contacts, allewing signakHto-gQ to" I r;

thereby restoring all the circuits to their original condition. 5 I t will benoted that a conductor is extended backfrom relay L to electromagnet G. The purpose of this is to insure the deener ization of magnet G in case si nalH shou. d not clear. If the clearin of t e sig* nal alone were relied upon for energizing magnet G by breaking its maintaining .circuit, this magnet would not be denergized in case the signal mechanism I should fail so as to prevent the signal H from clearing, and consequently the preceding signal. would be prevented from clearing; but by means of the conductor above mentioned, if signal II should fail to clear, magnet G will be denergized when the signal reaches relay L, since this relay, in closing its contacts, short-cir cuits magnet G through the contacts of relay L,- the train axles, and the upper rail A; therebycausing the magnet to drop its armatures.

I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the a pended clai1ns',to cover all modifications w rich are within the scope "of my invention.

What I claim asnew and desire to secure by Letters Patent of the United States, is,

1. In combination with an electrically operated road having both rails conductively continuous for all currents, normally opencircuited transformers" adapted to impress an alternating voltage in the track rails, normally closed cirouited sources of voltage connected across said rails, meansin circuit with-said sources responsive to the ap roach of a train to close the circuit of a trans ormer ahead of the train, and signal controllin devices responsive to the alternating vol tage impressed on the rails .by the transformers when their circuits are closed.

2., In combination with an electrically o I erated road havin both rails conductive y continuous for all currents, transformers adapted to impress an alternating voltage on the track rails, normally closed circuited sources of voltage connected across said rails, relays in circuit with said sources controllin the circuits of said transformers, and signa controlling devices responsive to the voltage impressed on the rails by the transformers when their circuits are closed.

3. In combination with an electrically o erated road having both rails conductive y continuous for all currents, transformers and signal controlling relays connected at intervals across said rails, said transformers being normally open-circuited, and meansconnected across saidcontinuous rails.at points between the transformers and relays responsive to the approach of a train for closing the circuit of a transformer ahead of the train.

4. In combination with an electrically o I erated road having both rails conductive y continuous for'all, currents, transformers and signal controlling relays connected at intervals across said rails, said transformers being normally open-circuited, normally closed-circuited sources of voltage connected across said rails at points between the transformers and relays, and devices in circuit with said sources controlling the circuits of said transformers.

5. In combination with an electrically operated road having both rails conductively continuous for all currents, transformers and signal controlling relays connected at intervals across said rails, said transformers bein normally open-circuited, normally close circuited sources of voltage connected across said rails atpoints between the transformers I and relays, and devices in circuit with said sources controlling the circuits of said transformers, the voltage impressed on the rails by said sources being different in character from that of said transformers and ineffective for operatin said signal controlling relays.

6. In com ination with an electrically operated road having both rails oonductively continuous for all currents, transformers and signal controlling relays connected at intervals across said rails, said transformers being normally open-circuited, normally closed circuited sources of voltage connected across and relays, and devices ,in circuit with said said rails at pointsbetween the transformers sources controlling the circuits of said transformers, the signal'controllin'g relays being responsive only to current from said transformers.

7 In combination with an electrically operated road'having both rails conductively continuous for all currents, sources of low voltage high-frequency current connected across said rails at intervals, normally opencircuited transformers connected to the rails, means in circuit with said sources for closing the circuits of said transformers, and signal controlling relays responsive to the alternatin voltage impressed on the rails by the transformers when their circuits are closed.

8. In combination with an electrically o erated road havin both rails conductive y continuous for al currents, transformers connected at intervals across the rails, normally open contactsin series with said transformers, I electroma nets controlling said contacts, sources- 0 low-voltage high-frequency current connected across the rails, relays in circuit with said sources controlling said electromagnets, and signal controlling relays responsive to the voltage impressed on the rails b said transformers when said contacts are c osed.

In witness whereof, I have hereun to set my hand this-9th day of January, 1907 LAURENCE A. HAWKINS. Witnesses:

BENJAMIN B. HULL, HELEN ORFORD. I 

